Tissue-Removing Catheter for Body Lumen

ABSTRACT

A catheter for removing tissue from a body lumen includes a rotatable cutter. The cutter includes an annular cutting tip at the distal end portion of the cutter for removing tissue from the body lumen. An axial cavity is defined by an interior surface of the cutter and extends proximally from the annular cutting tip toward the proximal end portion of the cutter. An eccentric opening extends from the central cavity through the cutter to allow tissue removed from the body lumen by the annular cutting tip to pass proximally through the eccentric opening toward an interior passage of the catheter body. The offset opening is offset from the longitudinal axis of the cutter.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional ApplicationSer. No. 61/736,169, filed Dec. 12, 2012, the entirety of which ishereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present invention generally relates to a tissue-removing catheterfor a body lumen.

BACKGROUND

Vascular disease frequently arises from the accumulation of atheromatousmaterial on the inner walls of vascular lumens, particularly arteriallumens of the peripheral and other vasculature, especially peripheralarteries, resulting in a condition known as atherosclerosis.Atherosclerosis occurs naturally as a result of aging, but may also beaggravated by factors such as diet, hypertension, heredity, vascularinjury, and the like. Atheromatous deposits can have widely varyingproperties, with some deposits being relatively soft and others beingfibrous and/or calcified. In the latter case, the deposits arefrequently referred to as plaque.

Vascular disease can be treated in a variety of ways, including drugs,bypass surgery, and a variety of catheter-based approaches, includingthose which rely on intravascular debulking or removal of theatheromatous or other material occluding a blood vessel. A variety ofmethods for cutting or dislodging material and removing such materialfrom the blood vessel have been proposed, generally being referred to asatherectomy procedures. Atherectomy catheters intended to cut or excisematerial from the blood vessel lumen may employ a rotatable cuttingblade (or other tissue-removing element) which can be advanced into orpast the occlusive material in order to cut and separate such materialfrom the blood vessel lumen.

It is desirous to provide catheters which can access small, tortuousregions of body lumens and which can remove tissue and/or otheroccluding materials from within body lumens in a controlled fashion. Inone instance, it may be desired to provide atherectomy catheters whichcan facilitate capturing atheromatous materials. The catheters andmethods for use in a variety of body lumens, including but not limitedto coronary, peripheral, and other arteries, and other body lumens.

SUMMARY

In one aspect, a catheter generally comprises an elongate catheter bodyconfigured for insertion into a body lumen of a subject. The catheterbody has opposite distal and proximal ends, a longitudinal axisextending between the distal and proximal ends, and an interior passageextending along the longitudinal axis. A cutter is located generally atthe distal end of the catheter body. The cutter has a proximal endportion, a distal end portion, and a longitudinal axis extending betweenthe proximal and distal end portions. The cutter is rotatable relativeto the catheter body generally about its longitudinal axis. The cutterincludes an annular cutting tip at the distal end portion of the cutterfor removing tissue from the body lumen, an axial cavity defined by aninterior surface of the cutter extending proximally from the annularcutting tip toward the proximal end portion of the cutter, and aneccentric opening extending from the central cavity through the cutterto allow tissue removed from the body lumen by the annular cutting tipto pass proximally through the eccentric opening toward the interiorpassage of the catheter body. The eccentric opening is offset from thelongitudinal axis of the cutter body.

In another aspect, a catheter generally comprises an elongate catheterbody configured for insertion into a body lumen of a subject. Thecatheter body has opposite distal and proximal ends, and a longitudinalaxis extending between the distal and proximal ends. A cutter is locatedgenerally at the distal end of the catheter body for rotation generallyabout the longitudinal axis of the catheter body. The cutter has aproximal end portion, a distal end portion, and a longitudinal axisextending between the proximal and distal end portions. The cutterincludes a cutting tip at the distal end portion of the cutter forremoving tissue from the body lumen; and a deployment mechanismoperatively connected to the cutter and the catheter body forselectively deploying and stowing the cutter. The deployment mechanismincludes a camming element operatively connected to the cutter to allowfor rotation of the cutter relative to the camming element, wherein thecamming element is moveable axially with the cutter relative to thecatheter body, and a cutter housing hingedly attached adjacent thedistal end of the catheter body, the cutter housing being pivotableabout a hinge axis generally transverse to the longitudinal axis of thecatheter body and having a cutter window. The deployment mechanism isconfigured such that: proximal movement of the camming element relativeto the catheter body and the cutter housing drives the cutter housing topivot about the hinge axis so that the deployment mechanism opens,whereby the cutting tip extends through the cutter window and isexposed, and distal movement of the camming element relative to thecatheter body and the cutter housing drives the cutter housing to pivotabout the hinge axis so that the deployment mechanism closes, wherebythe cutting tip is stowed in the cutter housing and unexposed.

In yet another embodiment, a catheter generally comprises an elongatecatheter body configured for insertion into a body lumen of a subject.The catheter body has opposite distal and proximal ends, a longitudinalaxis extending between the distal and proximal ends, and an interiortissue-transport passage extending along the longitudinal axis. A cutteris located generally at the distal end of the catheter body for rotationgenerally about the longitudinal axis of the catheter body. The cutterhas a proximal end portion, a distal end portion, and a longitudinalaxis extending between the proximal and distal end portions. The cutterincludes an annular cutting tip at the distal end portion of the cutterfor removing tissue from the body lumen, and a tissue passage defined byan interior surface of the cutter extending proximally from annularcutting tip, and having an inlet adjacent the annular cutting tip and anoutlet extending through the cutter. A driveshaft is operativelyconnected to the proximal end portion of the cutter for selectivelyimparting rotation to the cutter relative to the catheter body. A cutteradaptor is operatively connected to the cutter and defines an internalpassage connecting the tissue passage of the cutter with the interiortissue-transport passage of the catheter body. The cutter adaptordefines a shearing edge proximal of and adjacent to the outlet of thetissue passage. The cutter is rotatable relative to the shearing edge tocut tissue passing proximally into the internal passage through theoutlet of the tissue passage.

In another aspect, a catheter generally comprises an elongate catheterbody configured for insertion into a body lumen of a subject. Thecatheter body has opposite distal and proximal ends, a longitudinal axisextending between the distal and proximal ends, and an interiortissue-transport passage extending along the longitudinal axis. Adriveshaft extends axially through the interior tissue-transport passageand is configured for rotational about its longitudinal axis. A cutteris located generally at the distal end of the catheter body for rotationgenerally about the longitudinal axis of the catheter body. The cutterhas a proximal end portion, a distal end portion, and a centrallongitudinal axis extending between the proximal and distal endportions. The cutter includes an annular cutting tip at the distal endportion of the cutter for removing tissue from the body lumen. A tissuepassage is defined by an interior surface of the cutter extendingproximally from annular cutting tip, and having an inlet adjacent theannular cutting tip and an outlet extending through the cutter. A stemat the distal end portion is operatively connected to the driveshaft forselectively imparting rotation to the cutter about the centrallongitudinal axis of the catheter. The stem defines an eccentric cammingportion that is radially offset from the central longitudinal axis ofthe cutter. A cutter adaptor defines an internal passage connecting thetissue passage of the cutter with the interior tissue-transport passageof the catheter body. The cutter adaptor includes an internal thread inthe internal passage. The stem and the internal thread are configuredsuch that the eccentric camming portion of the stem rides along theinternal thread as the cutter is rotated by the driveshaft.

In yet another aspect, a catheter generally comprises an elongatecatheter body configured for insertion into a body lumen of a subject.The catheter body has opposite distal and proximal ends, a longitudinalaxis extending between the distal and proximal ends, and an interiortissue-transport passage extending along the longitudinal axis. Adriveshaft extends axially through the interior tissue-transport passageand is configured for rotational about its longitudinal axis. A cutteris located generally at the distal end of the catheter body for rotationgenerally about the longitudinal axis of the catheter body. The cutterhas a proximal end portion, a distal end portion, and a centrallongitudinal axis extending between the proximal and distal endportions. The cutter includes an annular cutting tip at the distal endportion of the cutter for removing tissue from the body Lumen, and atissue passage defined by an interior surface of the cutter extendingproximally from annular cutting tip, and having an inlet adjacent theannular cutting tip and an outlet extending through the cutter. A guardis disposed immediately distal of the annular cutting tip of the cutter.The guard is configured to cover at least about one half of acircumferential portion of the annular cutting tip to inhibit tissueremoved from the body lumen and disposed in the tissue passage fromexiting the cutter distally through the annular cutting tip.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective of an embodiment of atissue-removing catheter, including a removable handle attachable to aproximal end of the catheter;

FIG. 2A is an enlarged fragmentary side elevation of a distal endportion of the tissue-removing catheter, with the tissue-removingcatheter in a retracted position;

FIG. 2B is similar to FIG. 2A, except a cutter housing is removed toshow hidden components;

FIG. 3 is a longitudinal section of the distal end portion of thetissue-removing catheter of FIG. 2A;

FIG. 4A is an enlarged side elevation of the distal end portion of thetissue-removing catheter, with the tissue-removing catheter in adeployed position;

FIG. 4B is similar to FIG. 4A, except the cutter housing is removed toshow hidden components;

FIG. 5 is a longitudinal section of the distal end portion of thetissue-removing catheter of FIG. 4A;

FIG. 6A is an exploded perspective of the distal end portion of thetissue-removing catheter;

FIG. 6B is an enlarged, exploded perspective of the cutter housing ofthe tissue-removing catheter;

FIG. 7 is an enlarged, front perspective of the cutter of thetissue-removing catheter;

FIG. 8 is an enlarged, rear perspective of the cutter of thetissue-removing catheter;

FIG. 9 is an enlarged, longitudinal section of the cutter;

FIG. 10 is a front perspective of a second embodiment of a cutter forthe tissue-removing catheter of FIG. 1;

FIG. 11 is a front elevation of the cutter of FIG. 10;

FIG. 12 is a longitudinal section of the cutter taken in the planeindicated by line 12-12 in FIG. 11;

FIG. 13 is a longitudinal section of the cutter taken in the planeindicated by line 13-13 in FIG. 11;

FIG. 14 is a front perspective of a third embodiment of a cutter for thetissue-removing catheter of FIG. 1;

FIG. 15 is a front elevation of the cutter of FIG. 14;

FIG. 16 is a longitudinal section of the cutter of FIG. 14;

FIG. 17 is an enlarged, exploded perspective of the cutter and a distaltube piece of the tissue-removing catheter of FIG. 1, including a secondembodiment of a guard of the tissue-removing catheter;

FIG. 18 is a longitudinal section taken through the assembled cutter,distal tube piece, and guard of FIG. 17;

FIG. 19 is an enlarged front elevation of the distal tube piece of thetissue-removing catheter of FIG. 1, with an external thread of a cutterstem shown in broken lines;

FIG. 20 is an enlarged rear elevation of the distal tube piece of thetissue-removing catheter of FIG. 1, with an external thread of a cutterstem shown in broken lines;

FIG. 21 is an enlarged longitudinal section similar to FIG. 3 with acutter housing and a catheter body removed therefrom, a driveshaft beingshown broken for illustrative purposes;

FIG. 22 is an front perspective of a second embodiment of a distal tubepiece for the tissue-removing catheter of FIG. 1;

FIG. 23 is a front elevation of the distal tube piece of FIG. 22, withan external thread of a cutter stem shown in broken lines;

FIG. 24 is a rear elevation of the distal tube piece of FIG. 22, with anexternal thread of a cutter stem shown in broken lines;

FIG. 25 is an enlarged front perspective of a second embodiment of aproximal tube piece for the tissue-removing catheter of FIG. 1;

FIG. 26 is a front elevation of the proximal tube piece of FIG. 25, withan external thread of a driveshaft shown in broken lines;

FIG. 27 is an enlarged longitudinal section similar to FIG. 21,including the second embodiments of the proximal and distal tube pieces;

FIG. 28 is an enlarged side elevation of a distal end portion of asecond embodiment of the tissue-removing catheter, with a cutter of thetissue-removing catheter in a deployed position;

FIG. 29 is a longitudinal section of the distal end portion of thetissue-removing catheter of FIG. 28;

FIG. 30 is an enlarged front perspective of a cutter of thetissue-removing catheter of FIG. 28;

FIG. 31 is an enlarged side elevation of the cutter of FIG. 30;

FIG. 32 is an enlarged longitudinal section of the cutter and a distaltube piece of the tissue-removing catheter of FIG. 28; and

FIG. 33 is a cross section of the cutter and the distal tube piece takenthrough the plane indicated by the line 33-33 in FIG. 32.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, several embodiments of a tissue-removingcatheter for removing tissue from a body lumen are disclosed. Inparticular, the illustrated catheter embodiments are suitable forremoving tissue from a body lumen, and are particularly suitable forremoving (i.e., excising) plaque tissue from a vessel (e.g., peripheralartery or peripheral vein). Features of the disclosed embodiments,however, may also be suitable for treating chronic total occlusion (CTO)of blood vessels, particularly peripheral arteries, and stenoses ofother body lumens and other hyperplastic and neoplastic conditions inother body lumens, such as the ureter, the biliary duct, respiratorypassages, the pancreatic duct, the lymphatic duct, and the like.Neoplastic cell growth will often occur as a result of a tumorsurrounding and intruding into a body lumen. Removal of such materialcan thus be beneficial to maintain patency of the body lumen. While theremaining discussion is directed toward catheters for removing tissuefrom and penetrating occlusions in blood vessels (e.g., atheromatous orthrombotic occlusive material in an artery, or other occlusions inveins), it will be appreciated that the teachings of the presentdisclosure apply equally to other types of tissue-removing catheters,including, but not limited to, catheters for penetrating and/or removingtissue from a variety of occlusive, stenotic, or hyperplastic materialin a variety of body lumens.

Referring now to FIGS. 1-9, a first embodiment of a catheter, and moreparticularly, a tissue-removing catheter, is generally indicated byreference numeral 10. Briefly, the tissue-removing catheter 10 includesan elongate tubular catheter body 12 having opposite proximal and distalends, a central longitudinal axis LA₁ (FIG. 2) extending between thedistal and proximal ends, and an internal tissue-transport passage 14(FIGS. 3 and 5) extending generally along the longitudinal axis of thebody. Referring to FIGS. 2-5, a rotatable cutter, generally indicated at16, is operatively connected to the distal end of the catheter body 12for removing tissue from body lumen. In particular, in the illustratedembodiment the cutter 16 is operatively connected to a cutter adaptor,generally indicated at 18. A driveshaft 20 (FIGS. 3 and 5), whichincludes an external helical thread 22, drives rotation of the cutter 16and also transports or moves removed tissue proximally within thetissue-transport passage 14 of the catheter body 12. A deploymentmechanism, generally indicated at 24, configures the tissue-removingcatheter 10 between a retracted position in which the cutter is notexposed for cutting (FIGS. 1, 2A and 3) and a deployed position in whichthe cutter is exposed for cutting (FIGS. 4A and 5). As explained indetail below, in the illustrated embodiment the cutter adaptor 14functions as part of the deployment mechanism 24 and also constitutes,by virtue of an additional function, as a tissue shearing member tofacilitate proximal transport of the removed tissue within the cutteradaptor.

Referring still to FIG. 1, the catheter body 12 is configured (e.g.,sized and shaped) for intravascular introduction into the target artery,although as explained above, the catheter body may be configured forintraluminal introduction into other target body lumens other than atarget artery. Although not illustrated, the catheter 10 may beconfigured for introduction of the catheter body 12 over a guidewire toa target site within the vasculature. In particular, the catheter 10 maybe configured for “over-the-wire” introduction when a guidewire channelextends fully through the catheter body 12 or for “rapid exchange”introduction where the guidewire channel extends only through a distalportion of the catheter body. In other cases, it may be possible toprovide a fixed or integral coil tip or guidewire tip on the distalportion of the catheter 10 or even dispense with the guidewire entirely.Moreover, a flexible, atraumatic distal tip (not shown) may be securedto the distal end of the illustrated catheter to facilitate insertion ofthe catheter. For convenience of illustration, guidewires will not beshown in any embodiment, but it should be appreciated that they can beincorporated into any of these embodiments.

The dimensions and other physical characteristics of the catheter body12 may vary depending on the artery (or other body lumen) of the subjectwhich is to be accessed. The catheter body 12 is generally flexible andmay in one embodiment have a length in the range from 50 cm to 200 cmand an outer diameter in the range from 1 French to 12 French (0.33 mm:1 French), such as from 3 French to 9 French. The catheter body 12 maybe composed of an organic polymer which is fabricated by extrusiontechniques. Suitable polymers include polyvinylchloride, polyurethanes,polyesters, polytetrafluoroethylenes (PTFE), silicone rubbers, naturalrubbers, and the like. Optionally, the catheter body 12 may bereinforced with a braid, helical wires, coils, axial filaments, or thelike, in order to increase rotational strength, column strength,toughness, pushability, and the like. For example, the catheter body 12may include a torque tube, as is generally known in the art. The outerdiameter of the catheter body 12 can be modified by heat expansion andshrinkage using conventional techniques. It will be appreciated that theconstruction and dimensions of the catheter body may be other thandescribed without departing from the scope of the present invention.

The catheter body 12 of the present embodiment may include an urgingmechanism (not shown) to urge the cutter into engagement with the bodylumen wall during treatment. For example, the urging mechanism maycomprise a portion of the catheter body adjacent to and proximal of thecutter that is biased to (e.g., permanently deformed in) a double-bentor double-curved shape to urge the cutter toward a wall of a body lumento enhance treatment. A suitable urging mechanism is disclosed in U.S.Pat. No. 7,708,749, the relevant teaching of which is herebyincorporated by reference. In other embodiments, the urging mechanismmay take many other suitable forms. The catheter may not include anurging mechanism without departing from the scope of the presentinvention.

Referring to FIGS. 3 and 5, as set forth above, the catheter 10 includesthe rotatable cutter 16 and the driveshaft 20 for imparting rotation ofthe cutter. The driveshaft 20 extends along the tissue-transport passage14 of the catheter body 12 and is selectively movable axially therein(i.e., generally along the longitudinal axis LA₁ of the body) to actuatethe deployment mechanism 24, as explained in detail below. A distal endportion of the driveshaft 20 is operatively connected to the rotatablecutter 16 for selectively driving rotation of the cutter generally aboutthe longitudinal axis LA₁ of the catheter body 12. In the illustratedembodiment, the distal end portion of the driveshaft 20 is fixedlysecured to the cutter 16. The shank of the driveshaft 20 (i.e., the partof the driveshaft not including the thread 22) is generally flexible andmay be formed from one or more coils (e.g., stainless steel coil(s)), ora torque tube (e.g., a polyimide tube with a layer of braided stainlesssteel wire embedded therein). The body of the driveshaft 20 may have avery high torsional stiffness and sufficient tensile strength, but whichis generally laterally flexible. Depending upon the desired torquetransmission, diameter and flexibility, any of a variety of othermaterials and constructions may also be used.

In the illustrated embodiment, the helical thread 22 on the exterior ofthe driveshaft 20 extends along the length of the driveshaft andfunctions as a transport mechanism for transporting removed tissueproximally within the tissue-transport passage 14 of the catheter body12. Accordingly, the threaded driveshaft 20 functions as an auger or ascrew conveyer, whereby rotation of the driveshaft imparts rotation ofthe helical thread 22, which moves removed tissue proximally within thecatheter body 12. In the illustrated embodiment, the thread 22 is aright-handed thread (as viewed from the proximal end of the driveshaft20), such that rotation of the driveshaft 20 clockwise (as viewed fromthe proximal end of the driveshaft 20) transports the tissue proximally.The tissue transport passage 14 and driveshaft thread 22 may extend backto the proximal end portion of the catheter body 12 and may empty into atissue receptacle (not shown). The tissue transport passage 12 anddriveshaft thread 22 may stop short of the proximal end portion of thecatheter body 12. The thread 22 may be formed on the driveshaft 20 in asuitable manner.

In one example, shown in FIGS. 3 and 5, the cross-sectional dimension(e.g., inner diameter) of the tissue-transport passage 14 is slightlygreater than the major diameter of the exterior thread 22 on thedriveshaft 20 so that there is a small radial gap (or play) between theexterior thread on the driveshaft and interior surface defining thetissue-transport passage 14. In this example, the radial gap is such soas not to inhibit or impede rotation and axial movement of thedriveshaft 20 in tissue-transport passage 14, and at the same time,substantially inhibit tissue from passing between the thread 22 on thedriveshaft 20 and the interior surface defining the tissue-transportpassage. For example, the diameter of the tissue-transport passage 14may be from about 0.001 in (0.025 mm) to about 0.020 in (0.508 mm)greater than the major diameter of the exterior thread 22. It isunderstood that other types of transport mechanisms (e.g., aspirationdevices, or other types of auger transport mechanisms) may be used withthe catheter 10, in lieu of the helical thread 22 on the driveshaft 20.It is also understood that the transport mechanism may be omittedwithout departing from the scope of the present invention. For example,a chamber may be provided proximal or distal the cutter 16 to storeremoved tissue.

Referring to FIG. 1, the proximal end of the driveshaft 20 is operablyconnected to a cutter motor 30 (broadly, a cutter driver) to impartrotation of the driveshaft 20 relative to catheter body 12. In oneexample, the cutter motor 30 is disposed within a handle 32 (shown witha cover removed in FIG. 1) that is releasably connectable to theproximal end of the catheter 10. For example, in addition to the cuttermotor 30, the handle 32 may house a power source 34 (e.g., batteries)for the cutter motor 30, a microswitch (not shown) for activating cuttermotor, and a catheter connector 36 for operatively connecting the motorto the proximal end portion of the driveshaft 20. In some embodiments,the cutter motor 30 can rotate the driveshaft 20 between 1,000 rpm and10,000 rpm or more, if desired. As explained in more detail below, thehandle 32 may include one or more input devices, such as lever 40, whichcontrols the major operations of the catheter 10, such as axial movementof the driveshaft 20 to actuate the deployment mechanism 24, androtation of the driveshaft 20 and the cutter 16 via the cutter driver30. It is understood that the driveshaft 20 may be driven in other wayswithout departing from the scope of the present invention.

As seen best in FIGS. 7-9, the rotatable cutter 16 has opposite proximaland distal ends and a longitudinal axis LA₂ extending therebetween. Thecutter 16 has a generally cylindrical distal cutting portion 42, aproximal stem 44 (broadly, a driveshaft-connection portion) forconnecting the cutter to the driveshaft 24, and a transitional portion46 intermediate the distal cutting portion and the stem. The distalcutting portion 42 has an outer cross-sectional dimension OD₁ (e.g., anouter diameter) that is greater than an outer cross-sectional dimensionOD₂ (e.g., an outer diameter) of the stem 44, and the exterior of thetransitional portion 46 tapers (e.g., necks down) longitudinally fromthe distal cutting portion to the stem. For reasons explained below, theexterior surface of the distal cutting portion 42 has a circumferentialgroove 48 formed therein. The cutter 16 may be formed as a single,one-piece construction, or may be formed from separate componentssecured to one another in a suitable manner, such as welding, soldering,adhesives, mechanical interference fit, threaded engagement and thelike. As a non-limiting example, the cutter 16 may be comprised ofsteel, tungsten carbide, tungsten carbide cobalt, tungsten carbidemolybdenum, silicon carbide, silicon nitride, ceramic, amorphous metalsor other materials and may be manufactured by methods including turning,grinding, sintering, electro-discharge machining (EDM), laser cutting,heat treating, precipitation hardening, casting or other methods.

Referring still to FIGS. 7-9, the distal cutting portion 42 of thecutter 16 includes an annular cutting tip 50 at the distal end thereof,and an axial cavity 52, defined by an interior surface of the cutter 16,extending from the cutting tip toward the stem 44 of the cutter. In onenon-limiting example, the annular cutting tip 50 is beveled from anexterior surface of the cutter toward the interior surface to define thesharp, distal cutting edge. The beveled, annular cutting tip 50 createsa “negative angle of attack.” The cutting tip 50 may be formedseparately from the distal cutting portion 42 of cutter 16 and attachedthereto, or the cutting tip may be formed integrally with the distalcutting portion of cutter. In the embodiment illustrated in FIGS. 7-9,the annular cutting tip 50 has a generally smooth surface. The cuttingtip may be of other configurations without departing from the scope ofthe present invention. For example, other configurations of the cuttingtip are disclosed below regarding FIGS. 10-16.

The stem 44 connects the cutter to the distal end of the driveshaft 20such that rotation of the driveshaft imparts rotation of the cutterabout its longitudinal axis LA₂ (i.e., the rotational axis of the cutteris coincident with the central longitudinal axis of the cutter). In theillustrated embodiment, and as shown in FIG. 9, a central longitudinalaxis LA₃ of the stem 44 is coincident with the central longitudinal axisLA₂ of the cutter 116. The stem 44 defines a bore 62, having a centralaxis coincident with the central longitudinal axis of the stem, in whichthe distal end of the driveshaft 20 is secured. For example, the distalend of the driveshaft 20 may be secured in the bore 62 by soldering,welding, adhesive, press-fit interference, crimping, or in other ways.In the present illustrated embodiment, the stem 44 includes a helical,exterior thread 64 running along the length of the stem to furtherfacilitate proximal transport of removed tissue, as explained in moredetail below. In the illustrated embodiment (shown best in FIGS. 3 and5), the exterior thread 64 on the stem 44 is aligned (or mates) with thethread 22 on the driveshaft 20 to form a substantially continuous threadextending from the stern along the driveshaft. In one example, the pitchof the stem thread 64 is the same as the pitch of the driveshaft thread22, although the pitches may be different. In another embodiment, suchas shown in FIGS. 10-13, the stem 44 may be free from an exteriorthread.

As set forth above, the tissue removed from the body lumen by thecutting tip 50 passes proximally through the cutter 16, toward thetissue-transport passage 14 of the catheter body 12. In the illustratedembodiment, the cutter 16 has an eccentric opening 68 in communicationwith the axial cavity 52 to allow removed tissue to pass through thecutter. Together, the eccentric opening 68 and the axial cavity 52define a tissue passage extending through the cutter 16. Thus, as can beseen from FIG. 5, as the tissue is being removed, it enters the axialcavity 52, and then passes through the eccentric opening 68 and into thecutter adaptor 18, where it can be picked up by the stem thread 64and/or the driveshaft thread 22 (or other transport mechanism), andtransported proximally within tissue-transport passage 14. Referring toFIG. 9, the eccentric opening 68 in the cutter 16 is offset with respectto the longitudinal axis LA₂ (and rotational axis) of the cutter. Theeccentric opening 68 is shaped such that when viewed from the distal endof the cutter 16 looking proximally, the eccentric opening extendsaround the longitudinal axis LA₂ in an arc and does not intersect thelongitudinal axis of the cutter. In the illustrated embodiment (see bestin FIGS. 7-9), the eccentric opening 68 extends through the taperedtransitional portion 46 of the cutter 16, such that the eccentricopening (as defined by an axis AC₁ that is parallel to the interiorsurface of the transitional portion 46) extends at an angle α₁ that isneither coincident nor parallel with the longitudinal axis LA₂ (androtational axis) of the cutter. As a non-limiting example, the offsetangle α₁ may measure from about 15 degrees to about 60 degrees, and inone example, about 45 degrees, from the longitudinal axis LA₂ (androtational axis) of the cutter 16. It is understood that the cutter 16may be of other configurations in other embodiments of the catheterwithout departing from the scope of the present invention.

Referring to FIGS. 10-13, another embodiment of the cutter is indicatedat reference numeral 16′. This cutter 16′ is similar to cutter 16, andlike components are indicated by corresponding reference numeral plus aprime symbol. In this embodiment, the beveled, annular cutting tip 50′may include one or more raised elements 56 (e.g., breakers). In theillustrated embodiment, four raised elements 56 are formed on thebeveled, annular cutting tip 50′, although in other embodiments morethan four or less than four raised elements may be present. Duringremoval of tissue from the target body lumen, the raised elements 56produce a hammer-like impact against the tissue to be removed as thecutter 16′ is rotated. In the case where the tissue to be removed hasbrittle characteristics (e.g., has become calcified), the tissue will becrushed into smaller particles thereby facilitating its removal.Repeated rotation of cutter 16 will produce repeated hammer-like blowsof the cutter raised elements 56 against the tissue to be removed. Theraised elements 56 are disclosed in U.S. patent application Ser. No.12/958,488, filed Dec. 2, 2010, the relevant teachings of which relatingto the raised elements disclosed thereon are incorporated by referenceherein. The stem 44′ of the present cutter 16′ is also not threaded,unlike the stem 44 of the previous cutter 16. However, the cutter 16′could be provided with threads.

Referring to FIGS. 14-16, another embodiment of the cutter is indicatedat reference numeral 16″. This cutter 16″ is similar to cutter 16, andlike components are indicated by corresponding reference numeral plus adouble-prime symbol. In this embodiment, the annular cutting tip 50″includes one or more flutes 58 (i.e., spiral grooves) extending fromadjacent the cutting tip to the interior surface defining the axialcavity 52″. In the illustrated embodiment, the annular cutting tip 50″also includes the raised elements 56, disclosed above with respect toFIGS. 10-13, although the raised elements may be omitted in anotherembodiment. The flutes 58 are shaped and arranged to drive tissueproximally into the axial cavity 52″ as the tissue is removed from thebody lumen. The stem 44″ is also threaded, like the stem 44 of thecutter 16.

As set forth above, the catheter 10 includes the deployment mechanism 24for configuring the cutter 16 between the retracted position (FIGS. 1-3)and the deployed position (FIGS. 4A, 4B and 5). The deployment mechanism24 is connected to a deployment adaptor 70 at the distal end of thecatheter body 12. For purposes of the disclosure, the deployment adaptor70 is considered part of the catheter body 12, and in particular, partof the distal end of the catheter body. In the illustrated embodiment,the deployment mechanism 24 includes a cutter housing 74, defining acutter window 75, hingedly attached to the deployment adaptor 70 at thedistal end portion of the catheter body 12.

The cutter adaptor 18 is axially (i.e., proximally and distally)moveable relative to the cutter housing 74, whereby proximal movement ofthe cutter adaptor drives the cutter housing to pivot about its hingeaxis A_(H) to open the deployment mechanism 24 and expose the cuttingtip 50 through the cutter window 75 (FIG. 5), and distal movement of thecutter adaptor drives the cutter housing to pivot about its hinge axisto close the deployment mechanism so that cutting tip is retracted inthe cutter housing (FIGS. 2 and 3). The cutter adaptor 18 is axiallymoveable relative to the cutter housing 74 (and the catheter body 12) byaxially moving the driveshaft 20, which imparts axial movement to thecutter 16. Accordingly, the cutter adaptor 18 moves axially with thecutter 16, which is conjointly moveable by the driveshaft 20. In oneembodiment, the driveshaft 20 is axially moveable relative to thecatheter body 12 by actuating the lever 40 on the handle 32, which mayalso actuate the motor 30 to drive rotation of the driveshaft and thecutter 16.

Referring to FIGS. 2-6B, in the illustrated embodiment, the cutteradaptor 18 includes a proximal tube piece 76 and a distal tube piece 78(together defining an adaptor tube or adaptor tube assembly) connectedto a cradle-shaped, rotational bearing member 80 that receives andsupports the cutter 16. The bearing member 80 is received in the cutterhousing 74 and is axially slidable therein. In particular, in theillustrated embodiment, the bearing member 80 has an exterior surfacehaving an arcuate cross-sectional shape that is generally complementaryto the exterior arcuate cross-sectional shape of the cutter housing 74,such that the bearing member nests in the cutter housing. In theillustrated embodiment, the components of the cutter adaptor 18 areformed as separate components and secured to one another by in asuitable fashion, such as by adhesive, welding, fasteners, or the like.Alternatively, selective components (including all of the components)may be formed integrally as a single, one-piece component. For example,the tube pieces 76, 78 may be formed as a single, one-piece component.The respective components of the cutter adaptor 18, including the distaltube piece 78, the proximal tube piece 76, the bearing member 80, andthe cutter housing 74 may be formed from stainless steel or otherbiocompatible material.

The rotational bearing member 80 is configured to allow rotation of thecutter 16 generally about the longitudinal axis LA₁ of the catheter body12 relative to the cutter adaptor 18, while substantially inhibitingaxial movement of the cutter relative to the cutter adaptor, such thatthe cutter adaptor moves axially with the cutter. The rotational bearingmember 80 also retains the cutter 16 is proper position relative to thecutter adaptor 18 as the cutter is rotated by the driveshaft 20. To thisend, the bearing member 80 has an internal support surface having anarcuate cross-sectional shape that is generally complementary to theexterior arcuate cross-sectional shape of the distal tube piece 78 andthe annular cutting tip 50 of the cutter 16 for supporting the cutterand the distal tube piece. In the illustrated embodiment, the bearingmember 80 includes pins 82 received in the circumferential groove 48 inthe exterior surface of the cutter 16. The cutter adaptor 18, morespecifically, the rotational bearing member 80, includes a tongue 84extending distally relative to the cutting tip 50. As explained below,the tongue 84 interacts with a closing ramp follower 88 of the cutterhousing 74 when the cutter adaptor 18 is moved distally to facilitateretracting the cutter 16 within the cutter housing. The rotationalbearing member 80 may be of other configurations and types withoutdeparting from the scope of the present invention.

Referring to FIGS. 3-5 and 21, the proximal and distal tube pieces 76,78, respectively, together define an internal passage 86 of the cutteradaptor 18 in which a portion of the cutter 16 (e.g., the transitionaland proximal portions 46, 44 of the cutter) and a portion of thedriveshaft 20 (e.g., the distal end portion of the driveshaft) arereceived. As shown in FIG. 21, the exterior of the proximal tube piece76 has a transitional portion 79 a tapering proximally from therotational bearing member 80, and proximal portion 79 b that is receivedin the tissue-transport passage 14 at the distal end portion of thecatheter body 12 to connect the internal passage 86 of the adaptor tubeassembly with the tissue-transport passage 14. As explained below, theexterior of the proximal tube piece 76 interacts with an opening rampfollower 90 of the cutter housing 74 when the cutter adaptor 18 is movedproximally to facilitate opening of the deployment mechanism 24. Theopening ramp follower 90 and closing ramp follower 88 remain inoperative contact with the camming element (as described below) in allrelative positions of the cutter housing and camming element.

The cutter housing 74 is hingedly attached to the deployment adaptor 70at its proximal end via a hinge connector 92 (e.g., a hinge pin, atrunnion, a living hinge, or the like) on the deployment adaptor 70 (seeFIG. 6A). The hinge connector 92 enables the cutter housing 74 to pivot(broadly, deflect) relative to the catheter body 12, the cutter adaptor18, and the cutter generally transverse to the longitudinal axis LA₁ ofthe catheter body 12, for deploying and retracting the cutter 16, asshown in FIGS. 2-5. A tip (not shown) of the catheter 10 may be securedto the distal end of the cutter housing 74, such that the tip moves withthe cutter housing.

To open the deployment mechanism 24, thereby deploying the cutter 16,the driveshaft 20 is moved proximally, such as by moving the lever 40 onthe handle 32. As the driveshaft 20 is moved proximally, the openingramp follower 90 in the cutter housing 74 runs along the exterior of thecutter adaptor 18 (more specifically, the exterior of the proximal tubepiece 76) causing the cutter housing 74 to pivot (broadly, deflect)relative to the catheter body 12 and about the hinge axis. As the cutterhousing 74 deflects, the cutting tip 50 of the cutter 16 extends throughthe cutter window 75 in cutter housing, whereby the cutting tip 50 isexposed outside the cutter housing. As shown in FIG. 4A, when the cutter16 is in the deployed configuration, the longitudinal axis LA₂ of thecutter extends at an angle α₂ offset from a central longitudinal axisLA₄ of the cutter housing 74. This offset angle α₂ may measure fromabout 5 degrees to about 15 degrees. As seen in FIGS. 4 and 5, in thedeployed position, only a circumferential portion of the cutting tip 50(i.e., an exposed circumferential portion) extends through the window75, while the remaining circumferential portion of the cutting tip doesnot extend through the window and is not exposed (i.e., a non-exposedcircumferential portion). The ratio of the exposed circumferentialportion to the non-exposed circumferential portion is theeffective-exposure of the cutting tip 50. In the illustrated embodiment,less than half of the circumference of the cutting tip 50 is exposed, atany instantaneous time, as the cutter 16 is rotating, and therefore, theeffective-exposure of the cutting tip is less than 50%.

Referring to FIGS. 2B and 4B, the illustrated embodiment includes stops99 (only one stop is visible in FIGS. 2B and 4B) on the cutter adaptor18, and more specifically, on an exterior of the proximal tube piece 76,to restrict proximal movement of the cutter adaptor relative to thecutter housing 74. In the illustrated embodiment, the stops 99 aredefined by notches formed in the exterior of the proximal tube piece.The distal end of the catheter body 12, more specifically, the distalend of the deployment adaptor 70 in the illustrated embodiment, engagesthe stops 99 when the cutter 16 is fully deployed to inhibit furtherproximal movement of the cutter adaptor 18. Alternatively, the distalend of the deployment adaptor 70 engages the stops 99 if there is anattempt to force the cutter adaptor 18 proximally beyond its fullydeployed position.

To close the deployment mechanism, thereby retracting the cutter 16 inthe stowed configuration (as shown in FIGS. 1-3), the driveshaft 20 ismoved distally from its proximal position, such as by moving the lever40 on the handle 32, which may also turn off the cutter driver 30 andstop rotation of the cutter 16. As the driveshaft 20 is moved distally,which moves the cutter 16 and hence the cutter adaptor 18 distally, theclosing ramp follower 88 in the cutter housing 74 runs along the tongue84 at the distal end of the cutter adaptor, thereby driving the cutterhousing to pivot about the hinged axis toward the closed position. Asthe cutter housing 74 pivots toward the cutter 16, the cutting tip 50reenters the cutter housing through the cutter window 75. When thecutter 16 is in its fully retracted position inside the cutter housing74, the distal end of the tongue 84 is received in a tongue slot 98 toinhibit pivoting of the cutter housing 74 about the hinge axis. When thedriveshaft 20 is moved proximally, the tongue 84 withdraws from thetongue slot 98 to allow the cutter housing 74 to pivot about the hingeaxis. The shape of the tongue 84 and closing ramp follower 88 allows thecutter housing 74 to first pivot (upon retraction of the cutter 16) andthen allows the cutter to move axially into the cutter housing from thecutter window 75. The opposite happens when the cutter 16 is deployed.The cutter 16 first moves axially into the cutter window 75 and then thecutter housing 74 is then pivoted to expose the cutting tip 50. It willbe understood that the force for both deploying and retracting thecutter 16 is provided entirely by the user through movement of thecutter 16, cutter adaptor 18 and drive shaft 20.

As set forth above, and explained in more detail below, in oneembodiment it is desirous to have the removed tissue move proximallythrough the cutter 16 (e.g., move into the axial cavity 52 and throughthe eccentric opening 68 in the cutter) and into the cutter adaptor 18where it can be picked up and transported proximally within the catheter10 by the stem thread 64 and the driveshaft thread 22. To furtherfacilitate proximal movement of the removed tissue, the illustratedcatheter 10 also includes a guard 100 (broadly, a tissue deflector)connected to the cradle-shaped bearing member 80 to block removed tissuethat has entered the axial cavity 52 from reversing direction (i.e.,moving distally) and exiting the axial cavity back through the distalend of the cutter 16. The guard 100 is disposed generally immediatelydistal of the cutting tip 50 of the cutter 16, and extends radiallyinward from the bearing member 80 toward the cutter window 75 in thecutter housing 74 to cover the non-exposed circumferential portion ofthe annular cutting tip 50 that is disposed below the cutter window 75when the cutter is deployed. In other embodiments, the guard 100 maycover more or less than the non-exposed circumferential portion.

Referring to FIGS. 17 and 18, the guard 100 may include an externallythreaded auger member 101 extending outward from a face 100 a of theguard that opposes the cutting tip 50. As shown in FIG. 18, the augermember 101 extends through the annular cutting tip 50 and into the axialcavity 52. The auger member 101 is coincident with the centrallongitudinal axis LA₂ of the cutter 16. A terminal end 101 a of theauger member 101 is disposed within the axial cavity 52. The augermember 101 is stationary and the cutter 16 rotates around the augermember 101 so that removed tissue that accumulates in the axial cavityand wraps around the auger member will be directed proximally, towardthe eccentric opening 68 in the cutter. It is understood that the guard100 and/or the auger member 101 may be omitted from the catheter 10.

As explained in more detail below, in the embodiments illustrated inFIGS. 1-12, the cutter adaptor 18 (or at least a portion(s) thereof)constitutes (i.e., functions as) a “shearing member,” in addition toconstituting (i.e., functioning as) a “camming element” of thedeployment mechanism 24. It is understood that in at least someembodiments, the cutter adaptor 18 may constitute a “shearing member,”as described below, and not constitute a “camming element” or otherwiseform part of the deployment mechanism. Moreover, some other componentmay be a camming element, or the camming element may be omitted.Likewise, it is understood that in at least some embodiments, the cutteradaptor 18 may constitute a “camming element” or otherwise form part ofthe deployment mechanism, and not constitute a “shearing member.”Moreover, some other component may be a shearing member, or the shearingmember may be omitted.

The distal tube piece 78 of the present illustrated cutter adaptor 18constitutes the “shearing member.” Referring to FIGS. 19-21, in thisembodiment the distal tube piece 78 has an internal bearing surface 102at a distal end portion thereof that engages the exterior surface of thetransitional portion 46 of the cutter 16, and a counterbore 104extending through a proximal end toward the internal bearing surface andforming part of the internal passage 86 of the cutter adapter 18. (Theinternal bearing surface 102 is also visible in FIGS. 3 and 5, amongother views, but is not labeled.) As seen from FIG. 21, the internalbearing surface 102 has a generally conical shape, correspondinggenerally to the conical shape of the exterior surface of thetransitional portion 46 of the cutter 16. Circumferentially spaced apartchannels 106 extend longitudinally through the bearing surface 102 toform shearing edges 108. In the present embodiment, seen best in FIGS.19-21, the distal tube piece 78 (functioning as the “shearing member”)includes two longitudinally-extending channels 106 forming twodiametrically-opposing shearing edges 108, although it is understoodthat the distal tube piece 78 may have one shearing edge or more thantwo shearing edges without departing from the scope of the presentinvention. As can be seen from FIGS. 3, 5, and shown best in FIG. 21, acutter shearing edge 110 partially defining the eccentric opening 68 inthe cutter 16 interacts with the shearing edges 108 as the cutterrotates. That is, as tissue removed from the body lumen (e.g., bloodvessel) passes through the eccentric opening 68 in the cutter 16, theremoved tissue is sheared or cleaved between the respective shearingedges 108, 110. This shearing facilitates movement of the removed tissueproximally into the cutter adaptor 18 and toward the stem thread 64and/or the driveshaft thread 22. In the illustrated embodiment, theremoved tissue is sheared between the shearing edges 108, 110 at aboutevery 0.5 revolutions of the cutter 16.

Referring to FIGS. 19-21, the counterbore 104 is sized and shaped forreceiving the cutter stem 44 of the cutter 16. The longitudinal channels106 also extend through the interior surface defining the counterbore104 to form longitudinal shearing edges 112 at the counterbore 104. Asset forth above, in this embodiment the cutter stem 44 includes thehelical, exterior thread 64, which in the present embodiment is aright-handed thread. The exterior thread 64 (as shown in broken lines inFIGS. 19 and 20) on the cutter stem 44 interacts with the shearing edges112 at the counterbore 104 as the cutter 16 rotates (i.e., clockwiserotation as shown in FIGS. 10 and 11) to shear and pinch removedmaterial therebetween to facilitate proximal movement of the removedtissue within the cutter adaptor 18. In the present embodiment (shownbest in FIGS. 19-21), the major diameter of the stem thread 64 isslightly less than the inner diameter of the counterbore 104, so thatthere is small radial gap (i.e., small amount of play) between the stemthread and the shearing edges 112. The radial gap is such so as not toinhibit or impede rotation of the stem 44 in the counterbore 104, and atthe same time, provide this shearing or pinching of removed materialbetween the stem thread 64 and the shearing edges 112 to facilitateproximal movement of the removed tissue.

In the present embodiment (as seen best in FIG. 21), the internalpassage 86 defined by the proximal tube piece 76 has a diameter (i.e.,inner cross-sectional dimension of the proximal tube piece) at thetransitional portion 79 a of the proximal tube piece 76 that tapersproximally to a constant, uniform diameter at the proximal portion 79 bof the proximal tube piece. The tapering internal passage 86 at thetransitional portion 79 a is significantly greater than the majordiameter of the stem thread 64 and/or the driveshaft thread 22 such thattissue may pass between the interior surface of the transitional portionof the proximal tube piece and the stem thread and/or the driveshaftthread without undergoing significant shear. The diameter of theinternal passage 86 at the proximal portion 79 b of the proximal tubepiece 76, on the other hand, is slightly greater than the major diameterof the driveshaft thread 22 so as not to inhibit or impede rotation ofthe driveshaft 20 in the proximal tube piece 76, and at the same time,substantially inhibit removed tissue from passing between the driveshaftthread 64 and the interior surface defining the constant inner diameterof proximal tube piece. In this way, the driveshaft 20 effectivelyfunctions as an auger or screw conveyor in the proximal portion 79 b ofthe proximal tube piece 76. In another embodiment, the major diameter ofthe portion of the driveshaft thread in the transitional portion 79 amay taper to correspond to the taper of the internal passage 86 so thatthe driveshaft 20 also effectively functions as an auger or screwconveyor in the transitional portion 79 a. In yet another embodiment,such as the embodiment illustrated in FIGS. 25-27 and discussed below,the proximal tube piece may have a substantially uniform inner diameter(i.e., substantially non-tapering) that is slightly greater than themajor diameter of the stem thread 64 and/or the driveshaft thread 22,and channels may extend longitudinally through the interior surfacethereof to define shearing edges, similar to the shearing edges 112 ofthe counterbore 104.

Referring to FIGS. 22-27, second embodiments of the proximal and distaltube pieces are indicated by reference numerals 76′ and 78′. The secondembodiment of the distal tube piece 78′ is shown in FIGS. 22-24 and 27,and the second embodiment of the proximal tube piece 76′ is shown inFIGS. 25 and 26. These embodiments of the proximal and distal tubepieces 76′, 78′, respectively, may be used with the catheter illustratedin FIGS. 1-21 by substituting the proximal and distal tube pieces 76,78, respectively, of the previous embodiment with the respective tubepieces 76′, 78′ of the present embodiment. The present proximal anddistal tube pieces 76′, 78′, respectively, are similar to the previouslydisclosed proximal and distal tube pieces 76, 78, and like componentsare indicated by corresponding reference numerals including primesymbols. In general, the operation of the catheter including one or bothsecond embodiments of the proximal and distal tube pieces 76′ and 78′for removing tissue from a body lumen may be substantially similar tothe exemplary operation set forth above with respect to the firstembodiment.

Referring to FIGS. 22-24 and 27, one difference between the presentdistal tube piece 78′ and the previously described distal tube piece 78is that the distal tube 78′ piece includes four (4) circumferentiallyspaced apart channels 106′ extending longitudinally through the bearingsurface 102′ and the interior surface of the distal tube piece to definefour (4) shearing edges 108′ at the bearing surface 102′, as opposed totwo (2) shearing edges 108 in the other embodiment, and four (4)shearing edges 112′ extending proximally within the distal tube piece78′. As shown in FIGS. 14 and 15, two of the four shearing edges 112′are defined by the intersection of the counterbore 104′ and two of thechannels 114′, and the remaining two of the four shearing edges aredefined by the intersection of two adjacent channels 106′. The shearingedges 108′, 112′ may be formed in other ways without departing from thescope of the present invention. As with the shearing edges 108 in thefirst embodiment, the shearing edges 108′ interact with the cuttershearing edge 110 to shear removed tissue passing through the eccentricopening 68 in the cutter 16. As opposed to the first embodiment,however, removed tissue is sheared at a quarter-revolution of the cutter16. Moreover, as with the shearing edges 112 in the first embodiment,the shearing edges 112′ interact with the stem thread 64 to shear orpinch removed tissue in the cutter adaptor to facilitate movement of thetissue proximally, toward the threaded driveshaft 20.

Referring to FIGS. 25-27, one difference between the present theproximal tube piece 76′ and the first proximal tube piece 76 is that thepresent proximal tube piece has a substantially uniform inner diameter(i.e., substantially non-tapering) along its length that is slightlygreater than the major diameter of the stem thread 64 and/or thedriveshaft thread 22. As shown in FIGS. 25 and 26, circumferentiallyspaced apart channels 114 (not present in the first embodiment) extendlongitudinally through the interior surface of the proximal tube piece76′ to define shearing edges 115, similar to the shearing edges 112′ ofthe counterbore 104′. More specifically, in the illustrated embodimentthese channels 114 extending longitudinally through the transitionalportion 79 a′ of the proximal tube piece 76′ that has a tapered exteriorsurface, but the channels do not extend through the proximal portion 79b′ of the proximal tube piece that is received in the distal end (e.g.,the deployment adaptor 70) of the catheter body 12. The shearing edges108′ in the proximal tube piece 76′ may be extensions of the shearingedges 112′ of the counterbore 104′. The exterior thread 22 on thedriveshaft 20 interacts with the shearing edges 108 as the cutter 16 anddriveshaft rotates to shear or pinch tissue therebetween to facilitateproximal movement of the removed tissue.

In an exemplary operation, the catheter 10 is inserted into the bodylumen (e.g., artery) such that the cutter 16 is positioned adjacent thetarget site. Fluoroscopy or other imaging techniques may be used tofacilitate placement of the catheter 10 in the body lumen. Duringplacement of the catheter 10 in the body lumen, the deployment mechanism24 is closed and the cutter 16 is in the stowed position. At the targetsite, the deployment mechanism 24 is opened, such as by moving the lever40 on the handle 32 proximally, to impart proximal movement of thedriveshaft 20 relative to the catheter body 12 and the cutter housing74, whereby the cutter adaptor 18 and the cutter 16 are also movedproximally relative to the cutter housing. As the cutter adaptor 18moves proximally, the tongue 84 at the distal end of the cutter adaptorwithdraws from the tongue slot 98 in the cutter housing 74, and openingramp follower 90 in the cutter housing runs along the exterior surfaceof the proximal tube piece 76. Thus, the cutter adaptor 18, morespecifically proximal tube piece 76, acts as a camming element foropening the deployment mechanism 24. As the proximal tube piece 76 ridesalong the opening ramp follower 90, the cutter housing 74 pivotsrelative to the cutter adaptor 18, the cutter 16, and the catheter body12, about the hinge axis A_(H), and a portion of the cutting tip 50 ofthe cutter extends through the cutter window 75 defined by the cutterhousing. As explained above, an urging mechanism (not shown) may urgethe cutting tip 50 toward the wall of the body lumen, and the offsetcutter housing 74 may also facilitates urging of the cutter toward thewall of the body lumen.

In one example, deploying the cutter 16 using the lever 40 also actuatesor turns on the cutter motor 30 to impart rotation of the driveshaft 20and the cutter. With the cutter 16 deployed and rotating, the catheter10 is moved distally within the body lumen, and the rotating cutting tip50 removes the tissue (e.g., plaque) from the body lumen (e.g., from anartery). As the tissue is being removed, the removed tissue movesthrough the annular cutting tip 50, into the axial cavity 52 in thecutter 16, and then passes into the eccentric opening 68. Using thecatheter 10 illustrated in FIGS. 1-21, at about every half revolution ofthe cutter 16, the cutter shearing edge 110 passes by one of theshearing edges 108′ of the internal bearing surface 102 to shear theremoved material disposed at that shearing location. The sheared tissuemoves proximally within the cutter adaptor 18, more specifically, withinthe counterbore 104, where the rotating stem thread 64 interacts withthe shearing edges 112,in the counterbore to pinch or shear the removedtissue and facilitate proximal movement of the tissue within the cutteradaptor, toward the driveshaft thread 22 and the tissue-transportpassage 14 of the catheter body. Within the tissue-transport passage 14,the removed tissue continues to be moved proximally by the driveshaftthread 22, which functions as an auger-like or conveyor-like transportmechanism.

Using the catheter 10 illustrated in FIGS. 1-21, and substituting therespective proximal and distal tube pieces 76, 78, respectively, for theproximal and distal tube pieces 76′, 78′, the cutter shearing edge 110passes by one of the shearing edges 108′ of the internal bearing surface102′ to shear the removed material disposed at that shearing location.The sheared tissue moves proximally within the counterbore 104′ of thedistal tube piece 78′, where the rotating stem thread 64 interacts withthe shearing edges 112′ in the counterbore to pinch or shear the removedtissue and facilitate proximal movement of the tissue toward proximaltube piece 76′. Within the proximal tube piece 76′, the rotatingdriveshaft thread 22 interacts with the shearing edges 108 to pinch orshear the removed tissue and facilitate proximal movement of thetissue-transport passage 14. Within the tissue-transport passage 14, theremoved tissue continues to be moved proximally by the driveshaft thread22, which functions as an auger-like or conveyor-like transportmechanism.

After completing a pass through the target site and removing a strip oftissue from the body lumen, the deployment mechanism 24 may be closedand the cutter motor 30 turned off (or alternatively, the motor mayremain on) by moving the driveshaft 20 distally relative to the catheterbody 12 using the lever 40 on the handle 32. As the driveshaft 20 ismoved distally, the closing ramp follower 88 runs along the tongue 84 todrive pivoting of the cutter housing 74 relative to the cutter adaptor18 and the cutter 16 about the hinge axis A_(H). When the cutter 16 isin its fully stowed position inside the cutter housing 74 (as shown, forexample, in FIGS. 1-3), the distal end of the tongue 84 is received inthe tongue slot 98 in the cutter housing 74 and the cutting tip 50 isreceived in the cutter housing and unexposed. With the cutter motor 30turned off (in one embodiment) and the cutter 16 in the retractedposition, the catheter 10 is moved proximally within the body lumen toallow for another pass through the target site.

Referring to FIGS. 28-33, another embodiment of a tissue-removingcatheter for removing tissue from a body lumen is generally indicated at210. This embodiment includes features that are similar, if notidentical, to features disclosed above with respect to the catheter 10disclosed above. Components of the present embodiment that are similaror identical to components of the catheter 10 are indicated bycorresponding reference numerals plus 200. The present catheter 210includes an elongate catheter body 212 that may be identical to thecatheter body 12, disclosed above. Other components of the presentcatheter 210 that may be identical to like components of the catheter 10in both structure and function and therefore will not be explained inany more detail, include: the threaded driveshaft 220, the cutterhousing 274 (including the closing and opening ramp followers 288, 290)hinged to the deployment adaptor 270 and pivotable about hinge axisA_(H), the cradle-shaped bearing member 280, and the proximal tube piece276. As explained below, the following components of the presentcatheter 210 are similar to like components of the catheter 10, albeitthese components differ from the previously described components in oneor both of structure and function: the cutter 216 and the distal tubepiece 278 (and thus, the cutter adaptor 218, although the proximal tubepiece 276 and the bearing member 280 are identical to the respectiveproximal tube piece 76 and the bearing member 80).

Referring to FIGS. 31 and 32, the cutter 216 has opposite proximal anddistal ends and a central longitudinal axis LA₅ extending therebetween.The cutter 216 has a generally cylindrical distal cutting portion 242, aproximal stem 244 (broadly, a driveshaft-connection portion) forconnecting the cutter to the driveshaft 220, and a generally cylindricalbearing-engagement portion 245 intermediate the distal cutting portionand the stem. The distal cutting portion 242 has an outercross-sectional dimension OD₃ (e.g., an outer diameter) that is greaterthan an outer cross-sectional dimension OD₄ (e.g., an outer diameter) ofthe stem 244, and the exterior of the bearing-engagement portion 245steps down from the distal cutting portion. The cutter 216 may be formedas a single, one-piece construction, or may be formed from separatecomponents secured to one another in a suitable manner, such as welding,soldering, adhesives, mechanical interference fit, threaded engagementand the like. As a non-limiting example, the cutter 216 may be comprisedof steel, tungsten carbide, tungsten carbide cobalt, tungsten carbidemolybdenum, silicon carbide, silicon nitride, ceramic, amorphous metalsor other materials and may be manufactured by methods including turning,grinding, sintering, electro-discharge machining (EDM), laser cutting,heat treating, precipitation hardening, casting or other methods.

Referring to FIGS. 30-33, the distal cutting portion 242 of the cutter116 includes an annular cutting tip 250 at the distal end thereof. Theannular cutting tip 250 is co-axial with the central longitudinal axisLA₅ of the cutter 216. In one non-limiting example, the annular cuttingtip 250 is beveled from an exterior surface of the cutter 216 toward theinterior surface to define the sharp, distal cutting tip. The beveled,annular cutting tip 250 creates a “negative angle of attack.” Thebeveled, annular cutting tip 250 may include raised elements (e.g.,breakers), similar to those described above with respect to FIGS. 1-13,and/or flutes, similar to those described above with respect to FIGS.14-16. The cutting tip 250 may be formed separately from the distalcutting portion 242 of cutter 216 and attached thereto, or the cuttingtip may be formed integrally with the distal cutting portion of cutter.The cutting tip may be of other configurations without departing fromthe scope of the present invention.

Referring still to FIGS. 30-33, the stem 144 defines a bore 162 in whichthe distal end of the driveshaft 120 is secured (as shown in FIG. 29).For example, the distal end of the driveshaft 220 may be secured in thebore 262 by soldering, welding, adhesive, press-fit interference,crimping, or in other ways. The stem 244 and the bore 262 havecoincident central longitudinal axes, both indicated by referencecharacter LA₆ (see FIG. 31). For reasons set forth below, the centrallongitudinal axes of the stem 244 and the bore 262 are radially offsetfrom the central longitudinal axis LA₅ of the cutter 216 (and theannular cutting tip 250). Accordingly, the rotational axis of thedriveshaft 220 at the stem 244 is radially offset from the centrallongitudinal axis LA₅ of the cutter 216 (and the annular cutting tip250). As explained below, although the rotational axis of the driveshaft220 at the stem 244 is radially offset from the central longitudinalaxis LA₅ of the cutter 216 (and the annular cutting tip 250), rotationof the driveshaft imparts rotation of the cutter and the annular cuttingtip about the longitudinal axis LA₅ of the cutter (i.e., the rotationalaxis of the cutter is coincident with the longitudinal axis LA₅ of thecutter). In the illustrated embodiment, the offset stem 244 has a flute263 (FIGS. 30, 31, and 33) extending along the length of the stem tofacilitate proximal movement of the tissue as the tissue exits thecutter 216, as explained below.

Referring to FIGS. 29 and 32, the cutter 216 has an eccentric passage253 (broadly, a tissue passage) extending from the annular cutting tip250 through the stem 244. As shown in FIG. 32, the eccentric passage 253has a central axis AC₂ that is angularly offset from the centrallongitudinal axis LA₅ of the cutter 216. As such, the tissue removedfrom the body lumen (e.g., blood vessel) by the cutting tip 250 passesthrough the cutter 216, via the eccentric passage 253, and into thecutter adaptor 218. A center C₁ is offset from the longitudinal axis LA₅of the cutter 216. The central axis AC₂ of eccentric passage 253 may beangularly offset from the central longitudinal axis LA₅ of the cutter216 by an angle α₃, which may measure from about 5 degrees to about 20degrees. The eccentric opening 253 intersects the longitudinal axis LA₅.This can be accomplished because of the offset of the stem 244. As aresult, the eccentric opening 253 can be larger than the eccentricopening 68 in the arrangement show in FIG. 9.

Referring to FIG. 32, the cutter 216 is received in the distal tubepiece 278 of the cutter adaptor 218 such that the bearing-engagementportion 245 engages a distal end of the distal tube piece and aninterior surface 220 of the distal tube piece. Thus, the distal tubepiece 278 functions as a rotational bearing that allows for the cutter216 to rotate about its central longitudinal axis LA₅ relative to thedistal tube piece 278 (including the other components of the cutteradaptor 218). Accordingly, although the rotational axis of thedriveshaft 220 at the stem 244 is radially offset from the centrallongitudinal axis LA₅ of the cutter 216 (and the annular cutting tip250), the cutter and the annular cutting tip rotate substantially aboutthe longitudinal axis LA₅ of the cutter. Otherwise, the cutter 216 wouldrotate about the central longitudinal axis LA₆ of the stem 244, whichwould cause the cutting tip move along an elliptical path (i.e., wobble)relative to the catheter body 212.

Referring to FIGS. 29 and 32, the distal tube piece 278 includes aninternal helical thread 215 extending along the length of the distaltube piece. Because the stem 244 is radially offset from the rotationalaxis of the cutter 216 (which is coincident with the centrallongitudinal axis LA₅ of the cutter), the stem of the cutter rides alongthe internal thread 215, in an eccentric or orbital motion, as the stemis rotated by the driveshaft 220. The interaction of the stem 244 withthe thread 215 drives proximal movement of the removed tissue disposedin the distal tube piece 278. In other words, the stem 244 functions topush the removed tissue in the distal tube piece 278 against theinternal thread 215, whereby the removed tissue moves proximally alongthe thread.

In an exemplary operation, the catheter 210 may be used in the samemanner as set forth above with respect to catheter 10. However, insteadof the stem 244 of the cutter 216 having an external thread tofacilitate proximal movement of the removed tissue, the interaction ofthe internal thread 215 of the distal tube piece 278 and the eccentricstem 244 facilitates proximal movement of the removed tissue, asdisclosed above.

Having described embodiments of the invention in detail, it will beapparent that modifications and variations are possible withoutdeparting from the scope of the invention defined in the appendedclaims.

When introducing elements of the present invention or the preferredembodiments(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above constructions, products,and methods without departing from the scope of the invention, it isintended that all matter contained in the above description and shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:
 1. A catheter for removing tissue from a body lumen,comprising: an elongate catheter body configured for insertion into abody lumen of a subject, the catheter body having opposite distal andproximal ends, a longitudinal axis extending between the distal andproximal ends, and an interior passage extending along the longitudinalaxis; and a cutter located generally at the distal end of the catheterbody, the cutter having a proximal end portion, a distal end portion,and a longitudinal axis extending between the proximal and distal endportions, the cutter being rotatable relative to the catheter bodygenerally about its longitudinal axis, the cutter including an annularcutting tip at the distal end portion of the cutter for removing tissuefrom the body lumen, an axial cavity defined by an interior surface ofthe cutter extending proximally from the annular cutting tip toward theproximal end portion of the cutter, and an eccentric opening extendingfrom the central cavity through the cutter to allow tissue removed fromthe body lumen by the annular cutting tip to pass proximally through theeccentric opening toward the interior passage of the catheter body,wherein the eccentric opening is offset from the longitudinal axis ofthe cutter.
 2. The catheter set forth in claim 1, wherein the eccentricopening extends at an angle that is offset relative to the longitudinalaxis of the cutter.
 3. The catheter set forth in claim 2, wherein thecutter has a transitional portion tapering toward the proximal endportion, wherein the eccentric opening extends through the transitionalportion of the cutter.
 4. The catheter set forth in claim 1, wherein theeccentric opening extends at an angle measuring from about 15 degrees toabout 60 degrees offset from the longitudinal axis of the cutter.
 5. Thecatheter set forth in claim 1, further comprising a driveshaftoperatively connected to the proximal end portion of the cutter forselectively imparting rotation to the cutter.
 6. The catheter set forthin claim 5, wherein the driveshaft is received in the interior passageof the catheter body and includes an external thread for transportingremoved tissue proximally in the interior passage.
 7. The catheter setforth in claim 6, wherein the cutter includes a stem at its proximal endportion having a central axis generally coincident with the longitudinalaxis of the cutter, wherein the driveshaft is fixedly secured to thestem for imparting rotation to the cutter.
 8. The catheter set forth inclaim 7, wherein the stem includes an external thread for transportingremoved tissue proximally toward the driveshaft.
 9. The catheter setforth in claim 1, further comprising a stationary shearing edge adjacentto the eccentric opening in the cutter, wherein the cutter is rotatablerelative to the stationary shearing edge to cut tissue passingproximally through the eccentric opening.
 10. The catheter set forth inclaim 9, wherein cutter has a shearing edge partially defining theeccentric opening, the shearing edge of the cutter overlapping thestationary shearing edge in a radial direction relative to thelongitudinal axis of the cutter as the cutter rotates to shear tissuepassing proximally through the eccentric opening.
 11. The catheter setforth in claim 10, further comprising a shearing member secured to thecatheter body and defining the stationary shearing edge, wherein theshearing member has a bearing surface engaging an exterior of thecutter.
 12. The catheter set forth in claim 11, wherein the stationaryshearing edge is defined at the bearing surface.
 13. The catheter setforth in claim 12, wherein the cutter includes a stem at its proximalend portion, the catheter further comprising a driveshaft operativelyconnected to the stern of the cutter for selectively imparting rotationto the cutter, wherein the stem and the driveshaft each includes anexternal thread for transporting removed tissue proximally in theinterior passage of the catheter body.
 14. The catheter set forth inclaim 13, wherein the shearing member has a counterbore extending towardthe bearing surface and forming part of the interior passage of thecatheter body, and wherein the stem is received in the counterbore. 15.The catheter set forth in claim 14, wherein the counterbore defines aninternal shearing edge within the shearing member, and wherein thethread of the stem interacts with the internal shearing edge to shearand pinch removed material therebetween as the cutter rotates.
 16. Thecatheter set forth in claim 1, further comprising: a deploymentmechanism operatively connected to the cutter and the catheter body forselectively deploying and stowing the cutter, the deployment mechanismincluding a camming element operatively connected to the cutter to allowfor rotation of the cutter relative to the camming element, wherein thecamming element is moveable axially with the cutter relative to thecatheter body, and a cutter housing hingedly attached adjacent thedistal end of the catheter body, the cutter housing being pivotableabout a hinge axis generally transverse to the longitudinal axis of thecatheter body and having a cutter window, wherein the deploymentmechanism is configured such that: proximal movement of the cammingelement relative to the catheter body and the cutter housing drives thecutter housing to pivot about the hinge axis so that the deploymentmechanism opens, whereby the cutting tip extends through the cutterwindow and is exposed, and distal movement of the camming elementrelative to the catheter body and the cutter housing drives the cutterhousing to pivot about the hinge axis so that the deployment mechanismcloses, whereby the cutting tip is stowed in the cutter housing andunexposed.
 17. The catheter set forth in claim 16, wherein the cammingelement includes a tongue extending distally with respect to the annularcutting tip of the cutter, the cutter housing includes a closing rampfollower adjacent a distal end of the cutter housing, wherein theclosing ramp follower is adapted to run along the tongue as the cammingelement is moved distally to facilitate closing of the deploymentmechanism.
 18. The catheter set forth in claim 17, wherein the cutterdefines a tissue passage extending through the cutter from the annularcutting tip, wherein the camming element defines an internal passage incommunication with the tissue passage of the cutter for receivingremoved tissue passing through the cutter.
 19. The catheter set forth inclaim 18, wherein the internal passage defined by the camming element isin communication with the interior passage defined by the catheter body.20. The catheter set forth in claim 17, wherein the tongue comprises astraight distal portion for guiding the cutter into the cutter housingand an arcuate portion to permit movement of the cutter housing to coverand expose the cutter.
 21. The catheter set forth in claim 16, whereinthe cutter housing further comprises an opening ramp follower disposedfor driving the cutter housing to expose the cutter upon movement of thecamming element in the proximal direction.
 22. The catheter set forth inclaim 21, wherein the opening ramp follower and closing ramp followerremain in operative contact with the camming element in all relativepositions of the cutter housing and camming element.
 23. The catheterset forth in claim 1, further comprising: a guard disposed immediatelydistal of the annular cutting tip of the cutter, the guard configured tocover at least about one half of a circumferential portion of theannular cutting tip to inhibit tissue removed from the body lumen anddisposed in the axial cavity from exiting the cutter distally throughthe annular cutting tip.